Entomologists can’t always be good at naming. At least the metallic blue lady beetle, Curinus coeruleus, is easy to remember, as well as identify.
C. coeruleus is a native of South America which has traveled all over the world, where it has largely been introduced by humans as a means of controlling insect pests such as mealybugs, whitefly, and psyllids (plant lice) via predation. It eats a number of insect species which harm crops.
I’m pretty sure what I caught here is a Curinus coeruleus emerging as an adult from its larval form. When the adult left, the expended shell remained stuck to my house. (This could be an adult eating something, which then remained stuck to my house, but the thing it’s sitting on looks like a metallic blue ladybug larva, and it was split open all down the back.)